In many enterprises (e.g., companies, governmental organizations, educational or research organizations, and so forth), communications networks are implemented to enable the transport of information among users and devices. Examples of such networks include local area networks (LANs), wide area networks, the Internet, and so forth.
Communications networks typically include switching nodes (such as Ethernet switches) that are able to receive packets, read the target address of each received packet, and forward each packet to the appropriate port associated with the target network segment. A switching node (or more simply “a switch”) provides switching at the physical and data link layers of the OSI (open systems interconnection) reference model. Switching at layers 2 and 3 of the OSI reference model involves a combination of switches and routers, with the routers making network- and transport-level decisions relative to establishment of a network path.
To reduce the likelihood of failures of communications networks, communications networks often use failure management schemes that are able to overcome points of failure within the communications networks. The failure management schemes allow re-routing around points of failure in the communications networks. In layer 2, this can be accomplished by building a loop-free topology, such as by using techniques described in IEEE (Institute of Electrical and Electronics Engineers) 802.1D or other techniques.
However, in some communications networks with failure management schemes, loops can occur, where a loop results from a combination of one or more network paths (and any nodes in those one or more network paths) that cause one network node to be connected back to itself through the combination of one or more network paths (and any nodes in those one or more network paths). The presence of loops may cause various issues in communications networks, including flooding of the networks with multicast or broadcast packets.